Use mirrors to shine light into a shadow, and use sticky notes or draw on the mirror to make (reverse) images in the patch of light.
Science content (2016 curriculum):
Physics: Light and Sound (1)
Earth/Space: Sun, Moon, Solar System, Universe (1, 4, 6)
Science topic (2005 curriculum connection):
Earth and Space Science: Stars and Planets (grade 3)
Physical Science: Light and Sound (grade 4)